We have described an inspirable (previously referred to as "inhalable") dust spectrometer in Published UK Patent Application No. 2,129,335A. The device described specifically therein, however, is not easily adaptable to miniaturization to produce a personal spectrometer capable of being carried continuously by a wearer and giving a representative picture of the exposure of the wearer to dust. Personal dust samplers are known and some are currently marketed, but in general these provide only a limited amount of information on dust collected during a sampling period, often solely a weight of so-called "total" or "respirable dust" collected. There are a few small cascade impactors commerically available and which do fractionate dust sampled, but none incorporates features yielding an inspirable dust fraction, and although these can be carried on the body as personal samplers, they also tend to be very expensive. It is an aim of the present invention to provide a personal dust sampler which selects an inspirable fraction of airborne dust and then collects a number of sub-fractions thereof from which biologically-relevant information can be obtained.